Pull gun



Nov. 12, 1968 SAUTER ET 3,410,128

PULL GUN 2 Sheets$heet 1 Filed Oct. 13, 1966 mm Q m M gwwwmmwsm mwm m NAM B wm wS 0 Nu wfi D E D @Q 8 wm & m M Y ww w BA 5 United States Patent3,410,128 PULL GUN Bobbie S. Sauter, Newport Beach, and Albert J.Wahlberg, Santa Ana, Califi, assignors to Standard Pressed Steel Co.,Santa Ana, Califi, a corporation of California Filed Oct. 13, 1966, Ser.No. 586,444 Claims. (Cl. 72-391) ABSTRACT OF THE DISCLOSURE A pull gunwhich is suited for the pulling of pullable stems or pin tails onfasteners which are secured by this means. The pull gun comprises arelatively fixed body housing and an axially movable set of pullingjaws. The puller carries screw threads on its exterior. A nut engagesupon the screw threads and is rotatably mounted with respect to thehousing. A motor is connected to rotate the nut. In the preferredstructure, the motor is a fluid driven rotary motor. The motor has adrive shaft, which drives an analog nut and screw in proportion to therotation of the main pulling nut and thus the amount of axial transportof the pulling stem. The analog nut and screw is connected to controlmeans to limit the maximum rotation of the motor and thus the maximumtransport of the pulling stem.

Background In the fastener art there are a number of fasteners which arepre-loaded and/ or set by pulling a stem thereon. Hand tools arenormally used for this pulling, and such hand tools must have largemechanical advantage to apply the necessary force to properly pull suchfasteners, especially in the larger sizes. It is clear that in rapidinstallation of such fasteners a proper, powered pull gun is desirable.Furthermore, it is desirable that such a pull gun has adequate force andproper controls, as well as being of light weight, so that it can beeasily managed, brought up to the fastener to be pulled, rapidly grippedthereon and accomplish the pull. Furthermore, it is desirable that sucha pull gun has such internal controls that it will automatically returnto the ready position. Such has not been previously available, despitethe growing need.

Description Accordingly, it is an object of this invention to provide apull gun which is particularly suited for the pulling of fastenershaving pullable stems or pin tails. It is an other object of thisinvention to provide a pull gun which is easily manageable and readilycontrollable so that such fasteners can be economically and convenientlysecured. It is a further object of this invention to provide a pull gunwhich is capable of high pulling force so that such fasteners ofrelatively large size may be properly and quickly secured. It is stillanother object of this invention to provide a pull gun for fastenershaving a pullable stem which incorporates means for ejecting the pulledstem so that in repetitive use, the previous stem is removed from thepulling jaws without interfering with the insertion of the next stem tobe pulled. It is a further object of this invention to provide a pullgun which has internal controls which limit the amount of stroke of thepulling jaws of the pull gun so that they stop in the position wherethey are ready for grasping on the pullable stem. Other objects andadvantages of this invention will become apparent from a study of thefollowing portions of this specification, the claims and the attacheddrawings.

FIG. 1 is a side elevational view of the preferred embodiment of thepull gun of this invention.

FIG. 2 is an enlarged partial longitudinal section therethrough.

FIG. 3 is an enlarged section taken generally along the line 33 of FIG.1.

FIG. 4 is a schematic pneumatic control circuit for the pull gun of FIG.1.

FIG. 5 is a side elevational view of a further embodiment of the pullgun of this invention.

FIG. 6 is an enlarged partial longitudinal sectional view thereof.

FIG. 7 is an enlarged section taken along the line 77 of FIG. 6.

FIG. 8 is an enlarged sectional view taken generally along the line 8-8of FIG. 5.

FIG. 9 is a sect-ion taken generally along the line 9-9 of FIG. 8.

Referring to the drawings in more particularity, the preferredembodiment of the pull gun of this invention is generally indicated at10. The pull gun 10 comprises a motor 12, which is preferably pneumatic.Valve assembly 14 is mechanically and pneumatically connected to themotor. The mechanical output of motor 12 is connected to gear case 16which is in turn connected to thrust unit 18.

As is seen in FIG. 2, motor 12 has an output shaft 20, which is anintegral part of the motor so that it rotates upon motor rotation. Drivegear 22 is secured to rotate with shaft 20. Housing 24 of gear case 16carries pin 26 therein. Idler gear 28 is mounted for rotation on thepin. Idler gear 28 is in gear tooth engagement with drive gear 22.

Housing 30 of thrust unit 18 carries bearings 32 and 34 therein. Theseare anti-friction bearings which rotatably support nut 36. Nut 36carries driven gear 38 which is in gear tooth engagement with idler gear28. Through the use of the idler gear, nut 36 turns in the samedirection as output shaft 20. Nut 36 is the pulling nut which draws uponthe pulling stern of the pull Nut 36 has a thrust face 40. Thrustwashers 42 are stacked against thrust face 40 and bear against housing30 through the outer race of bearing 32. Lubricant hole 44 permits thepassage of lubricant to the faces of the thrust washers so as tomaintain friction at a low level.

The interior of nut 36 is provided with threads 46. Pulling tube 48 hasexterior threads 50 engaged in the threads of nut 36. As is seen in FIG.3, pulling tube 48 is axially slotted with slots 52 and 54. Threadedpins 56 and 58 are respectively screwed into the housing 30 and extendinto the slot so as to prevent rotation of pulling tube 48. By thisconstruction, it can be seen that rotation of shaft 20 causes axialmovement of pulling tube 48 with respect to housing 30. Pulling tube 48has smooth exterior surfaces at 60 and 62 upon which are engaged seals64 and 66. These seals maintain lubricant within the portion of housing30 which is occupied by driven gear 38 and the several bearings.

Housing 30 extends forward to terminate in thnust face 68 which hasopening 70 therein. Pulling tube 48 extends forward to a position fullyforward against the interior of thrust face 68. The forward end ofpulling tube 48 has an opening 72 which is aligned with opening 70.Interiorly of pulling tube 48, it is provided with conical surface "74which acts .as a closer for pulling jaws 76 and 78. There are preferablythree or more such jaws, each provided with interior serrations 80 whichare particularly arranged to engage upon the stem to be pulled.Resilient ring 82 is engaged around the jaws to urge them into theclosed position. The front of the jaws facing opening 72 are arrangedwith an entrance cone 84 to guide a stem into the space between thejaws. When pull gun 10 is moved so that openings 70 and 72 accept a stemto be pulled, the stem engages upon the faces of the jaws moving thembackward with respect to the conical surface 74 to thus 3 permit them toopen to a suflicient extent to accept the stern. Resilient ring 82resiliently maintains the jaws in the proper position with respect toeach other.

Guide tube 86 is positioned within the interior of pulling tube 48 andis secured with respect thereto by means of threads 88. Spring 90 ispositioned around guide tube 86 and engages thrust tube 92. Thrust tube92. in turn engages the rear of the jaws 76 and 78 so as to urge themtoward thrust face 68 and thus toward the closed position by actuationof conical surface 74. However, both the closing caused by resilientring 82 and spring 90 are overcome by the inward thrust of a pull stemon the front of the jaws, to thus open them for acceptance and graspingof the pull stem.

In view of the fact that the pull stem on the fastener is torn loose asa part of the fastening operation, the pull stem must be disposed of.Guide tube 86 is in alignment with the jaws and is of suflicient size topass these broken off stems. Furthermore, the deflection tube 94 isaxially secured with respect to tube 86. Thus, broken off stems can passthrough tube 86 and deflection tube 94 to be discharged from the rear:of the thrust unit 18. Should it be undesirable to loosely dischargethese broken parts, a receiving bag 96 can be secured over ring 98 onthe rear of pulling tube 48.

Referring to FIGS. 1 and 4, control of motor 12 is accomplishment bysuitable control valving. Air inlet 100 is arranged to accept air from aconventional factory com pressed air source. Flow control valve 102 is aplain shutoff valve which can be infinitely variably controlled so as tocontnol that amount of air flow and thus the rotational speed of motor12. Reversing valve 104 is connected to receive air under pressure fromflow control valve 102. Reversing valve 104 has tubes 186 and 108connected thereto. Valve 104 is arranged so that when it is actuated,air under pressure is connected to tube 106 and tube 108 is closed. Whenreversing valve 104 is not actuated, the air under pressure is connectedto tube 108 while tube 106 is closed. Motor 12 is a commerciallyavailable motor having exhaust 110 and internal valving arranged so thatupon passage of air through tube 106, the motor rotates forward andexhausts air at 110. Upon pressurization of tube 118 the motor rotatesin the reverse direction and exhausts air at 110.

Referring again to FIG. 2, the interior of shaft 20 is threaded toaccept actuating rod 120. Actuating rod 120 is restrained from turningso that rotation of the motor causes the rod to move axially withrespect to the shaft. This is an analog of the movement of pulling tube48 with respect to housing 30. Rocker arm 122 is pivoted to the frame at124 and is connected to actuating rod 120 by means of link 126 so thatrocker arm 122 rocks as the motor rotates. Rocker arm 122 is connectedto valve plunger 128 of valve 112 by means of link 130. Valve plunger128 is arranged so that port 114 is closed in the position shown, whenpulling tube 48 is all the way fonward in housing 30. This stops fluidflow in the direction from tube 108 to tube 118 so that the pulling tube48 is stopped when the pulling tube reaches its forward position. Thisprevents damage to the structure.

In operation, a fastener with a pullable stem is inserted through anopening in the member to be fastened. The pull gun is moved up to thepullable stem and is thrust over the pullable stem so that the pullablestem moves the pulling jaw 76 and 78 backward toward an open position byovercoming resilient ring 82 and spring 90. These resilient means closethe jaws around the usual serrations on the pullable stem. Thereupon,the operator actuates the valves 102 and 104 by wrapping his hand aroundvalve assembly 14. Most fingers are engaged around the operating handleof valve 102, while the forefinger actuates valve 104 to the actuated,pulling position with air flow through tube 106, motor 12 and outexhaust 110. Air flow is controlled by valve 102 to motor 12 so that nut36 turns at the desired speed. At the same time, ac-

tuating rod axially moves in an analog to the axial movement of pullingtube 48. Rearward motion of the pulling tube, rightward in FIG. 2,causes pulling of the pullable stem on a fastener. At the same time,valve plunger 128 moves upward to open port 114. When the pullable stemis pulled loose, the operator releases his finger from reversing valve104. Thereupon, the air flow to the motor is reversed with air flowpassing through tube 108. Control valve 112, tube 118, motor 12 andexhaust 110. Upon reversal, pulling tube 48 moves forward and valveplunger 128 moves downward. When pulling tube 48 reaches its forwardmostposition, valve plunger 128 cut off air flow to stop motor 12. The pullgun 10 is then ready for acceptance of the next pullable stem. When thenext pullable stem is inserted into the jaws, the prior, broken off stemis thrust back through tube 86 to collect in receiving bag 96. Thisoperation can be continually repeated as long as the pulling isrequired. In most cases, especially with larger fasteners, the forcesand deflections involved are sufficient to fire the pulled stern throughtube 86 and deflector 94.

Referring now to FIGS. 5 through 9, a further embodiment of the pull gunof this invention is generally indicated at 132. Pull gun 132 closelyresembles the pull gun 10. It has a motor 134. Instead of a single valveassembly, it has two valve assemblies. Valve assembly 136 controls theamount of flow of pneumatic fluid while valve assembly 138 controls thedirection of fluid flow to motor 134, and thus the direction of motorrotation. Motor 134 drives the gears in gear case 140 which in turndrives thrust unit 142. The general organization of pull gun 132 is thesame as pull gun 10. The valve assemblies 136 and 138 are separatelyarranged for separate pistol grip holding and actuation, as compared tothe single valve assembly 14, which is arranged in axial alignment withthe motor 12.

Considering pull gun 132 in more detail, motor 134 has output shaft 144.Drive gear 146 is mounted on the shaft for rotation therewith. Gear case140 carries bushing 148 which supports the outboard end of shaft 144.Furthermore, gear case 140 carries pin 150 on which idler gear 152 isrotatably mounted. Idler gear 152 is in gear tooth engagement with drivegear 146.

Thrust unit 142 has nut 154 rotatably mounted therein. Nut 154 ismounted on antifriction bearings 156 and 158 which are of conventionaldesign, and are preferably the same as bearings 32 and 34. Thesebearings are carried in thrust unit housing 142. Nut 154 has driven gear158 mounted thereon so that rotation of the gear causes rotation of thenut. Gear 158 is in gear tooth engagement with idler gear 152.

Nut 154 has a thrust face 160 which bears against race 162 of thrustbearing 164. Race 166 faces race 162 and bears against the stationarypart of bearing 156. Retainer 168, see FIG. 7, is positioned betweenthese races. Thrust balls 170 are positioned in suitable holes inretainer 168. Preferably, in order to carry greater thrust loads, theballs 170 are spaced upon at least two different pitch diameters. In anyevent, the size of balls 170 and their number is adequate to carry thethrust load encountered by nut 154.

Pulling tube 172 extends through nut 154. Pulling tube 172 has threadson its exterior which engage with threads on the interior of nut 154, sothat when the nut rotates the pulling tube is axially moved. Rotation ofpulling tube 172 is prevented by pins similar to pins 56 and 58. One ofthese pins is illustrated at 174 in FIG. 5. Pulling tube 172 extendsforward and has a conical interior surface 176 which acts as a closerfor jaws 178 and 180 positioned within the pulling tube. Similarly tothe earlier described jaws, there are at least three jaws in the pullgun 132. Thrust tube 182 acts against these jaws, spring urgedidentically to thrust tube 92 to hold the jaws in position. Openings 184are provided in the front end of pulling tube 172 and in the front endof housing 156 to permit entry of a stem to be pulled into the jaws.Guide tube 186 extends into the rear of thrust unit 142 with deflectiontube 188 extending therefrom for discharge of pulled stems.

Valve assembly 136 is secured to gear case 140 so that the valveassembly extends away from the gear case to provide a comfortable pistolgrip manner of holding the pull gun 132. Air inlet 190 is connected tovalve assembly 136 and is adapted to be connected to a conventionalsource of plant compressed air, or other motive fluid supply. Air inlet190 is connected to valve 192, which simply provides an infinitelyvariable air flow control. The outlet from valve 192 is connected bymeans of a tube, not seen on the other side of FIG. 5, a portion ofwhich is seen at 194 in FIG. 8, to valve assembly 138. Connector 196 isconnected to the tube and to the valve assembly. Valve inlet 198 has anair inlet port 200 and a vent 202 to atmosphere. Valve 198 also haspassages 204 and 206 which has dividing web 210 across its center. Theweb 210 is arranged so that upon 90 rotation of the valve plug about itsaxis, connections between the motor passages are reversed with respectto fluid supply and exhaust. Thus, 90 rotation of the web causesreversal of the motor.

Eccentric pin 212 extends downwardly from the valve plug and is engagedby fork 214 on operating handle 216. Operating handle 216 is pivoted at218 and is arranged so that grasp around the pistol grip constructionincluding operating handle 216 causes rotation of the valve plug. Thus,valve 192 controls motor speed and valve 198 controls motor direction.Two pistol grip handles are provided for convenient handling of the pullgun 132.

Similarly to the gun, 10, the pull gun 132 is brought up to the stem tobe pulled and is inserted over the stem to be pulled so that the stemextends into jaws 178 and 180. Squeezing of operating handle 216 placesvalve plug 208 in such a position that the motor will be rotated in thepulling direction. 'I'hereupon, operation of valve 192 introduces air tothe motor and results in the pulling of pulling tube 172, the closing ofjaws 178 and 180 around the stem to be pulled and the pulling of thestem. When stem pulling is complete, operating handle 216 is releasedand the pulling tube is returned to the forward position.

No control valve, such as the control valve 112 in pull gun 10, is shownwith respect to pull gun 132. However, it will 'be apparent that such acontrol valve can be readily employed therein for the same purpose. Inthe present case however, the operator can readily hear from motoroperation when the pulling tube has reached the ends of its stroke, anduse this information to shut off the pull gun by closing valve 192 orreversing the pull gun by actuation of operating handle 216.

This invention having been described in its preferred embodiment, and anadditional embodiment disclosed, it is clear that it is susceptible tonumerous modifications and embodiments within the ability of thoseskilled in the art and without the exercise of the inventive faculty.Accordingly, the scope of this invention is defined by the scope of thefollowing claims.

We claim:

1. A pull gun, said pull gun comprising a housing, a rotary motormounted on said housing, a pulling tube mounted for nonrotative, axialmotion with respect to said housing and positioned within said housing,screw threads on said pulling tube, a nut mounted for rotation in saidhousing, said nut embracing said pulling tube and in engagement withsaid threads of said pulling tube, said rotary motor being connected torotate said nut with respect to said housing so as to move said pullingtube axially with respect to said housing, and pulling jaws mounted withrespect to said pulling tube, said pulling jaws being adapted to engageupon the pullable stem of a fastener.

2. The pull gun of claim 1 wherein said rotary motor is pneumaticallypowered, a flow control valve connected to said motor so as to controlthe amount of air flow to said motor to control the rotary speed of saidmotor, a reversing valve connected to said motor so as to control thedirection of rotation of said motor.-

3. The pull gun of claim 2 wherein said motor further has a stop valveconnected thereto, said stop valve being positioned in accordance withthe position of said pull tube with respect to said housing so as tostop motion of said pull tube with respect to said housing when saidpull tube reaches a predetermined position with respect to said housing.

4. The pull gun of claim 3 wherein said stop valve is connected byconnection means to 'be driven by said motor, said connection meanscomprising a screw thread connected to be driven by said motor, saidscrew thread being connected to move said valve 'so that said valvemoves proportionally to said pull tube and said valve is closed whensaid pull tube reaches its terminal position.

5. The pull gun of claim 1 wherein said pull tube has front end and arear end, said front end of said pull tube being open to permit entry ofa stem to be pulled into said jaws within said pull tube, said rear endof said pull tube being open to permit the discharge of a pulled stemfrom the rear of said pull tube.

6. The pull gun of claim 5 wherein a guide tube is positioned withinsaid pull tube, said guide tube being adapted to guide a pulled stem,said guide tube extending from adjacent said jaws within said pull tubeand extending out of the rear end of said pull tube.

7. The pull gun of claim 6 wherein a deflection tube is positionedwithin said pull tube and around said guide tube, a spring around saidguide tube, said spring engaging a thrust tube, said thrust tubeengaging said jaws so as to thrust said jaws with respect to said pulltube to urge said jaws toward a closed position.

8. The pull gun of claim 1 wherein a key is mounted on one of saidhousing' and said pulling tube, a slot on the other thereof, said keyengaging said slot to constrain said pulling tube with respect to saidhousing for said nonrotative axial motion therebetween.

9. The pull gun of claim 8 wherein said slot has ends and the engagementof said key with said slot ends determines the axial limit of motionofsaid pulling tube with respect to said housing.

10. The pull gun of claim 9 wherein said key is a pin secured in saidhousing and said slot is in said tube.

References Cited UNITED STATES PATENTS 2,342,089 2/1944 Rossmann 72-4543,028,987 4/ 1962 Van Hecke 72-391 3,095,106 6/1963 Morrison 72-3913,196,662 7/ 1965 Simmons 72391 FOREIGN PATENTS 535,5 84 10/ 1931Germany.

CHARLES W. LANHAM, Primary Examiner. G. P. CROSBY, Assistant Examiner.

